Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Condensed Financial Statements, Captions [Line Items]
Net income	$ 439,453	$ 290,278
Depreciation and amortization	117,387	110,750
Deferred income taxes	83,443	4,385
Net changes in working capital and other	(92,783)	87,418
Net cash provided by operating activities	547,500	492,831
Acquisition of business	(178,309)	0
Additions to equity investments	(23,338)	0
Additions to property, plant and equipment	(498,290)	(235,463)
Construction of assets pending sale-leaseback	(136)	(5,484)
Proceeds from disposition of assets	78	435
Proceeds from repayment of loan to affiliate	167	763
Proceeds from sales of equity securities	239,764	47,655
Purchase of securities and other investments	(232,286)	(2,961)
Settlements of derivative instruments	(2,297)	471
Net cash used for investing activities	(694,647)	(194,584)
Intercompany financing	0	0
Capitalized debt issuance costs	0	(2,221)
Dividends paid	(40,204)	(22,345)
Proceeds from Issuance of Long-term Debt	0	248,818
Proceeds from exercise of stock options	3,182	6,627
Repayments of Long-term Debt	0	(250,000)
Repurchase of common stock for treasury	(19,409)	(10,784)
Utilization of restricted cash	0	96,433
Windfall tax benefits from share-based payment arrangements	5,056	7,792
Net cash provided by financing activities	(51,375)	74,320
Net increase in cash and cash equivalents	(198,522)	372,567
Cash and cash equivalents at beginning of period	790,078	825,901
Cash and cash equivalents at end of period	591,556	1,198,468
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Net income	439,453	290,278
Depreciation and amortization	1,094	1,149
Deferred income taxes	(1,102)	(176)
Net changes in working capital and other	(458,336)	(317,955)
Net cash provided by operating activities	(18,891)	(26,704)
Acquisition of business	0
Additions to equity investments	0
Additions to property, plant and equipment	0	0
Construction of assets pending sale-leaseback	0	0
Proceeds from disposition of assets	0	0
Proceeds from repayment of loan to affiliate	0	0
Proceeds from sales of equity securities	239,764	3
Purchase of securities and other investments	(232,286)	0
Settlements of derivative instruments	0	0
Net cash used for investing activities	7,478	3
Intercompany financing	(130,832)	317,185
Capitalized debt issuance costs		(2,221)
Dividends paid	(40,204)	(22,345)
Proceeds from Issuance of Long-term Debt		248,818
Proceeds from exercise of stock options	3,182	6,627
Repayments of Long-term Debt		(250,000)
Repurchase of common stock for treasury	(19,409)	(10,784)
Utilization of restricted cash		96,433
Windfall tax benefits from share-based payment arrangements	5,056	7,792
Net cash provided by financing activities	(182,207)	391,505
Net increase in cash and cash equivalents	(193,620)	364,804
Cash and cash equivalents at beginning of period	753,881	803,320
Cash and cash equivalents at end of period	560,261	1,168,124
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income	446,858	312,038
Depreciation and amortization	114,432	107,191
Deferred income taxes	84,532	3,932
Net changes in working capital and other	(87,330)	95,909
Net cash provided by operating activities	558,492	519,070
Acquisition of business	(178,309)
Additions to equity investments	(23,338)
Additions to property, plant and equipment	(496,027)	(234,713)
Construction of assets pending sale-leaseback	(136)	(5,484)
Proceeds from disposition of assets	6	414
Proceeds from repayment of loan to affiliate	0	0
Proceeds from sales of equity securities	0	47,652
Purchase of securities and other investments	0	(2,961)
Settlements of derivative instruments	(2,297)	471
Net cash used for investing activities	(700,101)	(194,621)
Intercompany financing	139,130	(321,273)
Capitalized debt issuance costs		0
Dividends paid	0	0
Proceeds from Issuance of Long-term Debt		0
Proceeds from exercise of stock options	0	0
Repayments of Long-term Debt		0
Repurchase of common stock for treasury	0	0
Utilization of restricted cash		0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	139,130	(321,273)
Net increase in cash and cash equivalents	(2,479)	3,176
Cash and cash equivalents at beginning of period	6,973	2,517
Cash and cash equivalents at end of period	4,494	5,693
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income	(1,639)	(676)
Depreciation and amortization	1,861	2,410
Deferred income taxes	13	629
Net changes in working capital and other	7,664	(1,898)
Net cash provided by operating activities	7,899	465
Acquisition of business	0
Additions to equity investments	0
Additions to property, plant and equipment	(2,263)	(750)
Construction of assets pending sale-leaseback	0	0
Proceeds from disposition of assets	72	21
Proceeds from repayment of loan to affiliate	167	763
Proceeds from sales of equity securities	0	0
Purchase of securities and other investments	0	0
Settlements of derivative instruments	0	0
Net cash used for investing activities	(2,024)	34
Intercompany financing	(8,298)	4,088
Capitalized debt issuance costs		0
Dividends paid	0	0
Proceeds from Issuance of Long-term Debt		0
Proceeds from exercise of stock options	0	0
Repurchase of common stock for treasury	0	0
Utilization of restricted cash		0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	(8,298)	4,088
Net increase in cash and cash equivalents	(2,423)	4,587
Cash and cash equivalents at beginning of period	29,224	20,064
Cash and cash equivalents at end of period	26,801	24,651
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income	(445,219)	(311,362)
Depreciation and amortization	0	0
Deferred income taxes	0	0
Net changes in working capital and other	445,219	311,362
Net cash provided by operating activities	0	0
Acquisition of business	0
Additions to equity investments	0
Additions to property, plant and equipment	0	0
Construction of assets pending sale-leaseback	0	0
Proceeds from disposition of assets	0	0
Proceeds from repayment of loan to affiliate	0	0
Proceeds from sales of equity securities	0	0
Purchase of securities and other investments	0	0
Settlements of derivative instruments	0	0
Net cash used for investing activities	0	0
Intercompany financing	0	0
Capitalized debt issuance costs		0
Dividends paid	0	0
Proceeds from Issuance of Long-term Debt		0
Proceeds from exercise of stock options	0	0
Repayments of Long-term Debt		0
Repurchase of common stock for treasury	0	0
Utilization of restricted cash		0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	0	0
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	$ 0	$ 0